The evolution of the handling of credit card authorization transactions over the public switched telephone network is described in some detail in U.S. Pat. No. 4,796,292 issued Jan. 3, 1989, to Jerry S. Thomas and assigned to American Express Company of N.Y. A familiarity with the evolution of the public switched telephone network in the United States at the present date is helpful to an understanding of the present invention. The following background description summarizes portions of that discussion in conjunction with FIGS. 1, 2 and 3 which appeared in said U.S. Pat. No. 4,796,292.
The public switched telephone network (PSTN) as it existed before the Bell System break-up, is shown in grossly simplified form in FIG. 1. Each central office 10 provided service over telephone lines 14 to telephone stations 12. Central offices were connected to each other by trunks 16. Trunks are distinguished from telephone lines by the use of heavy lines. Each central office included a switch 8 for effecting connections between lines and lines, and lines and trunks. (Other switching facilities including tandem switches were provided for effecting trunk-trunk interconnections.) In general, a trunk is a 5 communication path in a network which connects two switching systems and tandem switches switch trunk to trunk. A trunk circuit, associated with the connection of a trunk to a switching system, serves to convert between the signal formats used internally in the switching system and those used in the transmission circuit, and it performs logic and sometimes memory functions associated with supervision. A line, on the other hand, is a pair of wires carrying direct current and analog communication signals between a central office and a customer's terminal; a line-side connection is a connection of central of f ice equipment to a line.
As the PSTN grew numerous interfaces and protocols developed and became standard. An interface is a shared boundary defined by common physical interconnection characteristics, signal characteristics, and meanings of interchanged signals. In telephony, the term "signaling" means the transmission of information to establish, monitor, or release connections and provide network control. Lines interfaced to central offices in ways which were distinct from those in which trunks interfaced to central offices. The physical connections were different, and even the number of wires could be different. The signalings were different. A protocol consists of procedures for communication between a sender and a receiver, of supervisory and address information, in order to establish and maintain a communications path. It is an agreed-to set of procedures so that communications between two ends will be intelligible in both directions (transmit and receive).
As time passed and AT&T faced competition from other common carriers (OCCs), the PSTN developed as shown, once again grossly simplified, in FIG. 2. Bell System central offices were still connected by trunks 16 to other central of f ices. An OCC such as MCI or Sprint would provide switches 18 which could be accessed from central office lines. The OCC switches would be interconnected via their own network trunks 24. In order to gain access to a common carrier other than AT&T, a telephone subscriber would be connected over a telephone line to his central office, through his central office and perhaps others, and finally over another telephone line associated with the OCC.
The quality of communications was generally not as good when going through the facilities of an OCC. This was the case even though the trunks actually used by the OCCs were leased from AT&T. The reason was related to the fact that poor performance is attributable most often to the inferior transmission performance on line-side connections. A typical AT&T Bell System call involved two lines 14, one at each end of the overall communication path; all other interfaces along the way involved trunk connections. An OCC, on the other hand, had an additional two line interface, as shown by numerals 20 and 22 in FIG. 2. Because each central office was connected over lines, not trunks, to an OCC switch, there were four line segments in each call, not just two.
In order that the common carriers other than AT&T be able to provide the same superior service following break-up of the Bell System, and in order that equal access to the local exchange users be given to all long distance Interstate Carriers, several access arrangements were made available. These access arrangements are known as Switched Access Services. The term Interexchange Customer or Carrier (IC) is used to denote any subscriber of Switched Access Services, including an Interexchange Carrier.
The geographic areas served by the Bell Operating Companies have been divided into Local Access and Transport Areas (LATAs). A typical LATA is shown in FIG. 3. A LATA is an area within which a Bell Operating Company--an Exchange Carrier (EC) or Local Exchange Carrier (LEC)--may offer telecommunication services. Interchange carriers (ICs) provide services between LATAS. The Interexchange Carriers are, AT&T, MCI, Sprint and others. The specific switched access arrangements offered by the Bell Operating Companies are known as the Feature Groups. An End Office (EO) is a Bell Operating Company switching system within a LATA where customer station loops (lines) are terminated for purposes of interconnection to each other and to trunks; a call may go directly from an End Office or be tandemed through a second office known as an Access Tandem (AT) to reach the IC. A tandem is a switching system in the message network that establishes trunk-to-trunk connections. As shown in FIG. 3, telecommunications within a LATA are handled by an EC, whereas telecommunications from one LATA to another are handled by an IC.
An IC under the present scheme designates a location within a LATA for the connection of its facilities with those of the Bell Operating Company which serves that LATA. There are about two hundred LATAs in the United States, and each of the Bell Operating Companies serves all or portions of multiple LATAs. The location of interconnection designated by the IC is called a Point Of Presence (POP), and typically it is at a building that houses an IC's switching system or facility node. An IC may have more than one POP within a LATA. In FIG. 3 a POP is shown by the numeral 30. An aggregate of one or more IC trunks is shown by the numeral 32. Instead of the POP being connected to a single central office, what usually happens is that it is connected by trunks to an Access Tandem (AT). The AT, shown by the numeral 26 in FIG. 3, is in turn connected to multiple central offices by means of trunks. An Access Tandem is a Bell Operating Company switching system that provides a traffic concentration and distribution function for inter-LATA traffic originating/terminating within a LATA. The AT thus provides the IC with access to more than one End office within the LATA. (A central office is an End Office).
For present purposes, what is important is that the LEC offers the IC a choice of four switched access arrangements called Feature Groups. Each IC, based on its own technical needs and business considerations, selects the access arrangement that it desires. The access arrangement involves a multiplicity of interfaces represented in FIG. 3 by the single trunk 28, it being understood that the drawing is only symbolic and there are in fact as many connections as there are maximum number of simultaneous calls that the IC expects to handle.
Feature Group A is a two-wire line-side connection between the IC and the EC. Feature Group A is not of particular interest because it is a line-side connection and is the only one of the four access arrangements for which the calling party is billed any local tariffed charges, i.e., message units. The other three Feature Groups involve trunk-side connections.
Feature Group B has an associated universal 7-digit (950-0/1XXX) access code and is used for the purpose of originating or terminating calls to or from subscribers. The XXX code is unique to each IC and, most importantly, it is the same throughout the country in all LATAs in which the IC has a presence. Feature Group B access arrangements include trunk signaling, trunk protocols, trunk transmission and trunk testing, and they provide answer and disconnect supervision. There can be two-wire and four-wire trunk terminating equipment, and, in general, there are supplemental features (as there are in the other Feature Groups) which are offered that allow an IC to specify substitutions for, or additions to, the standard arrangements as defined by the appropriate tariff.
Feature Group C exists now but is transitional. AT&T, whose trunk-side connections are presently Feature Group C, will convert to Feature Group D as it becomes available. Feature Group B involves 2-stage dialing, the kind of arrangement which existed before subscribers could select an IC other than AT&T. With an arrangement such as that shown in FIG. 2, a first number is dialed in order to gain access to a line which is connected to the OCC facility, after a connection is established, a second series of numbers are dialed to tell the OCC the personal identification number of the caller (PIN) and the destination of the call. As an option, when the connection is established, Automatic Number Identification (ANI) information may be forwarded to the OCC. Feature Group D, on the other hand, provides true "Equal Access" in that a customer can presubscribe to the long-distance carrier of his choice. By dialing the digit 1, his call will be connected to a Feature Group D trunk at the selected ICs Point Of Presence. There is only one number dialed, that of the destination. While the invention is applicable to Feature Group D service, the illustrative embodiment of the invention is described in terms of Feature Group B service.
Once a caller gains access to an ICs facilities, any subsequent dialing procedures are as specified by the IC for Feature Group A and Feature Group B service. Industry standards exist for the dialing plans for Feature Groups C and D. In-band tone dialing is usually employed, but in any event the EC is transparent to address signaling and data communications between the subscriber and the IC. As far as the interface between the EC and the IC is concerned, the IC can specify the type of supervisory signaling and interface to be used between the Bell Operating Company access facilities and the IC facilities at the ICs point of presence. The signaling options and interfaces that are available vary with the particular feature Group and tariff.
A prior art credit card authorization scheme is shown in FIG. 4. A credit card authorization terminal 30 is connected via an ordinary telephone line 34 to a central office 10. The authorization terminal includes a standard modem 32. At the beginning of the authorization process, the terminal dials a number which is associated with a line connected to a particular Value Added Network (VAN). The connection is established through central office 10. In the VAN 40, line 36 is connected to modem 38. Using the Visa protocol, the two modems communicate with each other. Modem 38 is connected via a digital interface to a Packet Assembler/Disassembler (PAD) 42 or some other multiplexer or concentrator within the VAN. The PAD establishes communication with a host over leased line 44 or some other communication channel.
As described above, the service establishment pays for a local call to the VAN. The VAN charges the credit card company for handling the call. There is no way to reduce the charges paid by the service establishment because a local call through the central office is being placed. It is also apparent that depending upon the location of the VAN in a particular city, the authorization terminals must have different numbers preprogrammed in their automatic dialers.
What is shown in FIG. 5 is a way that a service establishment can be relieved of paying for a local call. Also, the scheme of FIG. 5 must be employed when there is no VAN presence near the credit card authorization terminal. In this case the terminal establishes a call through the dial network 46, and over line 34 and trunk 48 to an AT&T facility 50. The AT&T lines are extended as an 800 call to modems in VAN 40. In this case the service establishment does not pay for the call; AT&T pays the Bell Operating Company. The credit card company picks up all charges of AT&T and the VAN. The arrangement of FIG. 5 is not preferred because of the cost of an 800 call.
The arrangement of FIG. 6 is not known to exist or to have existed but has been hypothecated in the said U.S. Pat. No. 4,796,292 as a kind of system which might be devised by a "telephone man". Lines 14 are connected to authorization terminals and are within the LATA of the Exchange Carrier. Some of the EC trunks, Feature Group B or D, are extended to the Point of Presence of an IC. A switch 54 is provided for extending trunks 28 to their destinations, in this case lines connected to modems and a PAD. Communications originate in the terminal, and a terminating modem in the POP is required to communicate with the modem in the terminal. Modems interface with lines, not trunks. A switch is the standard mechanism for interconnecting lines and trunks. Since only trunks come into the POP, a switch is necessary to connect an incoming trunk to a modem line (just as the switch of a central office connects a trunk and a subscriber line).
This approach allows a terminal to be connected to the host. The service establishment need not be billed for the call because with Feature Group B or D service, the IC pays the EC for each call which is placed. The IC is the only source of billing to the calling party, and with switching equipment having sufficient intelligence, it would be possible for the IC to bill the credit card company for calls placed to its host installation. This FIG. 6 arrangement is stated to be not feasible, however, because of the cost of switch 54. A typical modem is stated to cost in the order of $500. A switch for 100 lines is stated to cost in the order of $200,000. That would make the cost per modem not $500, but $2,500. That is stated to be impractical. And it is further stated there is no apparent way to avoid the use of the switch. There is a modem in each authorization terminal. There must be a modem at the other end of the connection. Modems have line connections. The EC/IC interface is over a Feature group B or D trunk. There is no way that a trunk can be interfaced with a conventional modem. Not only may the number of wires in the trunk be different from the number of wires at the modem input, but the signaling requirements are totally different. A costly switch is stated to be the device which allows a modem line to be connected to a trunk in the hypothecated solution of FIG. 6.
In U.S. Pat. No. 4,796,292 there is proposed an arrangement for authorizing credit card transactions wherein the credit card company obtains a 3-digit Customer Identification Code (CIC) in the manner of an Interexchange Customer or Carrier. At its POP there are provided dedicated, modems and a PAD or: other multiplexer or concentrator which is connected to the host. However, the modems are not conventional modems but are specially designed to provide a trunk-side interface. In the illustrated embodiment in that patent, E & M signaling and T1 interfaces are used. These trunk-side interface modems are stated to be only slightly more expensive than conventional modems. The proffered advantage is a reduction of the cost associated with local telephone calls involved in the transaction.
In the hardware embodiment of this proposal the Local Exchange Carrier (LEC) provides Feature Group B service on T1 access facilities using conventional E & M trunk protocol. The T1 link is connected to a conventional 24channel channel bank that includes a T1 trunk hardware interface. As stated the modem is designed to execute a trunk protocol so that at the two ends of the transmission path, namely the LEC and the modem, a trunk protocol is executed. In view of the fact that the modem is provided with a ground start interface the E & M channel bank cards must be modified to provide a ground start interface for the modem. An arrangement to effectuate this proposal is illustrated in FIG. 7 which comprises a combination of FIGS. 3 and 7B from U.S. Pat. No. No. 4,796,292. The channel bank is connected to the Access Tandem where the LEC establishes a trunk connection. The Access Tandem exercises a trunk protocol.